85 academic libraries from four countries and more than 170 public libraries have participated in the 2008 iteration of the Bibliotheksindex (BIX), a voluntary multi-level strategic benchmarking/ranking hosted and organized by the German Library Foundation. The start of systematic benchmarking in German libraries dates back into the early 1990s; initial projects were substantially driven by the Bertelsmann Foundation. Findings from these early initiatives resulted in the design of a nationwide statistical benchmarking instrument for public libraries which was established in 1999. Based on evidence from benchmarking and ranking initiatives on an international scale, an instrument for academic libraries was developed in 2004. Following the conceptual principles of the "Balanced Scorecard" approach, the Index currently processes data from-depending on library type-15 to 17 widely tested and communicable indicators in four strategic perspectives. After providing an insight into the conceptual framework of the BIX, the paper pinpoints improvements in the set of indicators, discusses the perception and acceptance of the instrument among libraries and highlights perspectives for further development. DEVELOPMENT German public libraries have a long tradition of measuring and comparing their performance. As one crucial stimulus for this tradition, Klug (2003) states a paper by Nick Moore in which he stressed the demand for 'easily applied measures that can be implemented at relatively low cost by busy librarians'. The first joint effort in testing, implementing and developing performance measures was marked in 1992 when the Bertelsmann Foundation initiated an extensive five year inter-library comparison study with 18 public libraries (Pröhl/Windau 1997a, 1997b). The project was based on the perception that inter-institutional comparisons could substitute the lack of competition in the public sector and be suitable as catalysts for continuous improvement. Based on the outcome of this pilot study, the Bertelsmann Foundation decided to launch, in partnership with the German Library Association (dbv), a consecutive project in order to introduce a nationwide benchmarking instrument for public libraries. The name chosen-BIX, a short form of Bibliotheksindex-bears a reference to DAX, the stock exchange